A Novel and Accurate Palpation Method for Identification of the L4 Spinous Process: A Preliminary Study of Accuracy

The purpose of this study was to assess a novel method of lumbar spinous process (SP) palpation by using magnetic resonance imaging (MRI) high-signal marker reference standards for verification.

Clinicians (doctors of chiropractic) in this study used either: (1) the standard/traditional method of identifying the L4 SP using the supracristal plane (n = 14) or (2) a novel method that manually induced sacral motion to identify the L5 and then the L4 SP (n = 54). The clinicians, blinded to the results of each other, used a grease pencil to mark the location identified as the L4 SP. An MRI high-signal marker then was taped across this location. The MRI scans were assessed by a radiologist, blinded to the palpation method, who extended a line posteriorly from the superior and inferior extent of the L4 SP and determined whether the high-signal marker was within the lines bordering the L4 SP (ie, "on-target").

Palpation using the traditional method showed a 35.7% accuracy, with 5 of 14 "on target" and all "off target" being too superior. Palpation using the novel method showed 77.8% accuracy, with 42 of 54 "on target" and 3 "off target" being too superior and 9 "off target" too inferior.

The novel method performed better than the traditional method. The novel method shows promise. Additional prospective research should be conducted to fully assess the accuracy of the novel method compared with traditional methods of palpation.